The pneumatic flotation machine protected by Russian Federation patent no. 2038865, B 03 D 1/24, is known. The machine contains a chamber with an aerator within the chamber, a foam overflow edge, a feed device as a tube with orifices and a circulation tube.
The pneumatic flotation machine is known which contains a chamber with an aerator within the chamber, a feed and discharge device, and an airlift arranged in the middle of the chamber and having a mixer in the lower part (see Russian Federation patent no. 2054972, B 03 D1/24).
The most similar to this in terms of its technical principle is the pneumatic flotation column which contains a cylindrical housing, consisting of the widened upper part and of the lower part, a feed device, designed as ejectors, a discharge device, aerators, a foam collecting container, a device, designed as an airlift, for the fine regulation of the pulp level in the machine, the annular baffle plate, which in cross section represents a triangle, the vertex of which is directed toward the machine axis, and a telescope-shaped chamber which is located in the widened housing part (see Russian Federation patent no. 2132749, B 03 D 1/24).
A known pneumatic flotation column, protected by Russian Federation patent no. 2132749, B 03 D 1/24, was implemented in the machine KFM-1400 (development of the “Uralmachanobr” Institute) and has the dimensions listed in Table 1.
TABLE 1Housing dimensions of the pneumatic flotation column KFM-1400BriefDesignation of the individualDimension indesignationhousing partsmeters (m)DDiameter of the widened upper2.2part of the cylindrical housingdDiameter of the lower part of the1.4cylindrical housingh1Height of the widened upper part4.24of the cylindrical housingh2Height of the lower part of the4.42cylindrical housingh1 + h2Overall height of the machine8.66
The known machine has the disadvantage that, when the required performance in terms of the feed and foam product is increased, the housing dimensions increase unjustifiably and thereby contribute to an appreciable rise in material intensity.
Furthermore, as compared with mechanical and pneumatic machines of the same volume, the known machine has a smaller area for foam formation and a smaller geometric length of the discharge weir (see Table 2).
TABLE 2Design parameters of the known flotation column andof the pneumatic/mechanical flotation machineFlotation machineDimensionKnown flotationFPM-3.2Design parameterunitcolumn(6 chambers)Machine volumem31919.2Area of foamm23.816.8formationLength ofm6.99.6discharge weir
On account of this, the flotation process in the known flotation column has a series of disadvantages: the aeroflocks which form (structures consisting of air bubbles and of mineral particles) dwell for longer in the pulp than in mechanical and pneumatic machines from the moment of occurrence to the moment of supply to the foam product, and, because of a lack of free space on the pulp surface, aeroflock collision and mutual annihilation processes take place in the foam layer. The disadvantages of the flotation process in the known flotation column cause the lowering of its performance downstream of the foam product and lead to the situation where it does not function with sufficient efficiency in flotation stages with a rich initial raw material, where a high yield of the foam product is required.